The field of art to which this invention pertains is coal liquefaction. More specifically, the invention relates to an improved process for the liquefaction of coal utilizing an oil shale residue catalyst comprising an organic and inorganic fraction.
In an effort to provide an economically commercial process for the liquefaction of coal, literally hundreds of processes have been proposed, each of which offers a somewhat different choice and/or combination of the many possible operating conditions and apparatus.
One problem with many prior art processes is that the quality and quantity of the coal derived hydrocarbon liquids have been inferior. This impediment is believed to be at least partly due to the fact that a suitable and economic means of promoting the coal liquefaction reaction via catalyst has not been available.
In U.S. Pat. No. 4,001,105 (Gifford II), a process is disclosed which produces hydrocarbonaceous products from carbonaceous materials, including coal, utilizing a catalyst which is derived from either raw oil shale or spent oil shale by activating the shale in the presence of steam at a temperature in the range of about 1000.degree. F. to about 1600.degree. F. At these conditions the oil shale becomes activated via at least partial decomposition of inorganic carbonates found therein. Moreover, at activation temperatures above 1000.degree. F., organic fractions present in the oil shale are also decomposed.
Defensive Publication No. 700,489 (Long et al.) discloses the extraction of ground oil shale or a retorted shale in the presence of a solvent at supercritical conditions which include a temperature in the range of 90.degree.-500.degree. F. and a pressure in the range of 750-5000 psig. The spent shale produced at these conditions is discarded from the process.
In U.S. Pat. No. 3,929,193 (Duke) organic matter is recovered from organic mineral-containing deposits such as oil shale by contacting the shale at a temperature range of 200.degree. to 1000.degree. F. with an extraction fluid and elemental sulfur. Extraction of the organic matter may be carried out either above ground after first mining the shale or "in situ" by injecting the extraction fluid and elemental sulfur into the organic mineral-containing deposit. Patentee does not teach any use for the extracted shale residue.
Finally, U.S. Pat. No. 4,438,816 (Urban et al.) teaches a process for the recovery of hydrocarbonaceous oil from oil shale. The process comprises heating the shale in the presence of a non-combustion supporting, non oil-miscible gas at a temperature range of about 650.degree. F. to 825.degree. F. to produce a material which is more readily conducive to the maximum recovery of the hydrocarbonaceous oil contained therein. The resulting treated shale is then solvent extracted with a normally liquid solvent at subcritical, reflux conditions to liberate any remaining organic hydrocarbonaceous fractions.
It is therefore an object of this invention to provide an improved coal liquefaction process. It is further an object of this invention to provide for an improved coal liquefaction process by employing an improved catalyst for use therein. Finally, it is also an object of this invention to provide for an improved coal liquefaction catalyst which comprises a pretreated oil shale residue.